Abstract: An example hydraulic system includes a hydraulic actuator; a pump driven by an electric motor and having an inlet port and an outlet port; a boost flow line configured to provide boost fluid flow or receive excess fluid flow; a reservoir fluid line fluidly coupled to a reservoir; and a valve assembly configured to operate in a plurality of states to allow the pump to operate in a closed-circuit configuration in which fluid discharged from the hydraulic actuator is provided to the inlet port of the pump or an open-circuit configuration in which fluid discharged from the hydraulic actuator is provided to the reservoir.

Abstract: An example hydraulic system includes a hydraulic cylinder actuator comprising a cylinder and a piston, wherein the piston comprises a piston head and a rod extending from the piston head, wherein the piston head divides an internal space of the cylinder into a first chamber and a second chamber, and wherein the hydraulic cylinder actuator is unbalanced; a first pump driven by a first electric motor to provide fluid flow to the first chamber or the second chamber of the hydraulic cylinder actuator to drive the piston; a boost flow line; a hydraulic motor actuator; and a second pump driven by a second electric motor, wherein the second pump is fluidly coupled to the boost flow line to provide boost fluid flow to the hydraulic cylinder actuator.

Abstract: An example hydraulic system includes a hydraulic actuator; a pump driven by an electric motor and having an inlet port and an outlet port; a boost flow line configured to provide boost fluid flow or receive excess fluid flow; a reservoir fluid line fluidly coupled to a reservoir; and a valve assembly configured to operate in a plurality of states to allow the pump to operate in a closed-circuit configuration in which fluid discharged from the hydraulic actuator is provided to the inlet port of the pump or an open-circuit configuration in which fluid discharged from the hydraulic actuator is provided to the reservoir.

Abstract: An example hydraulic system includes a hydraulic cylinder actuator comprising a cylinder and a piston, wherein the piston comprises a piston head and a rod extending from the piston head, wherein the piston head divides an internal space of the cylinder into a first chamber and a second chamber, and wherein the hydraulic cylinder actuator is unbalanced; a first pump driven by a first electric motor to provide fluid flow to the first chamber or the second chamber of the hydraulic cylinder actuator to drive the piston; a boost flow line; a hydraulic motor actuator; and a second pump driven by a second electric motor, wherein the second pump is fluidly coupled to the boost flow line to provide boost fluid flow to the hydraulic cylinder actuator.

Abstract: A method and system is provided for controlling a hydraulic actuator in a work machine by opening a load holding valve in a measured fashion in order to leak hydraulic pressure back into a depressurized portion of the hydraulic circuit, thereby minimizing or eliminating jerkiness in the actuator when the actuator is under an external load.

Abstract: In conventional load-sense systems, there is a delay between a hydraulic function being impeded by an external force and further motion of the function. This is typically due to cavitation on the low pressure side of the pump. Electro-hydraulic systems, however, typically respond very quickly because the low pressure side of the pump may be pressurized because the low-pressure side of the actuator may feed directly to the pump rather than going to tank. Thus, an operator cannot as easily rely on feedback for when a function has encountered an external load. This may result in loss of vehicle traction or other drawbacks. Therefore, provided is a system and method for mimicking a load-sense system's responsiveness using an electro-hydrostatic system via an induced passive or active time-delay.

Abstract: In conventional load-sense systems, there is a delay between a hydraulic function being impeded by an external force and further motion of the function. This is typically due to cavitation on the low pressure side of the pump. Electro-hydraulic systems, however, typically respond very quickly because the low pressure side of the pump may be pressurized because the low-pressure side of the actuator may feed directly to the pump rather than going to tank. Thus, an operator cannot as easily rely on feedback for when a function has encountered an external load. This may result in loss of vehicle traction or other drawbacks. Therefore, provided is a system and method for mimicking a load-sense system's responsiveness using an electro-hydrostatic system via an induced passive or active time-delay.

Abstract: An electro-hydraulic actuation system (901) includes an unbalanced hydraulic actuator (902) capable of motion in retraction and extension directions during movement of a load (904). A pump (204) provides a flow of fluid to the actuator. A displacement of the pump controls a velocity of the actuator during motion in the retraction and extension directions. An electric motor (202) drives the pump. Speed and direction of the electric motor affects the displacement of the pump. A controller (802) controls the speed and direction of the electric motor. A feedback device (228,248) is operable for sensing a system condition and for providing a feedback signal indicative of the sensed system condition to the controller. The controller is responsive to the feedback signal for determining an occurrence of an over-center load condition and for modifying the speed of the electric motor in response to the occurrence in an attempt to maintain the velocity of the actuator.

Abstract: A method and system is provided for controlling a hydraulic actuator in a work machine by opening a load holding valve in a measured fashion in order to leak hydraulic pressure back into a depressurized portion of the hydraulic circuit, thereby minimizing or eliminating jerkiness in the actuator when the actuator is under an external load.

Abstract: A method of controlling an electro-hydraulic actuator system having multiple functions includes the steps of: receiving input signals corresponding to a desired operation of the functions of the system; establishing an operating limit for the system; determining an operating characteristic of the system; using the operating limit and the determined operating characteristic to determine a limitation control factor; and influencing the received input signal with the determined limitation control factor for operating the system within the established operating limit.

Abstract: A flow management system capable of providing adjustable hydraulic fluid flow or pressure at a common line to supply bidirectional pumps in electro-hydrostatic actuation systems and conditioning re-circulated hydraulic fluid. The system enables flow sharing between multiple actuation systems and minimization of energy consumption by a power-on-demand approach and/or electrical energy regeneration while eliminating the need for an accumulator. The system has particular application to electro-hydrostatic actuation systems that typically include bi-directional electric motor driven pumps and unbalanced hydraulic actuators connected within closed circuits to provide work output against external loads and reversely recover energy from externally applied loads.

Abstract: An integrated fluid handling apparatus 10 includes a power take off device 108 having a rotating power take off mechanism 122, a hydraulic pump 104 having a rotating fluid pump mechanism 146, a flow torque tube 106, and an electric motor/generator 102 having a rotating electric power conversion mechanism 173. A rotational power transfer system includes connector devices 128, 138, 166 and 172 that are drivingly connected to and that drivingly connect the mechanisms 122, 146 and 173 in one mode of operation. The electric motor/generator 102 includes heat exchange fluid flow passages that establish a fluid flow path to the inlet of the pump. The mechanisms 122, 146 and 173, and the connector devices 128, 138, 166 and 172 are assembled and used as a whole within a housing, without externally exposed mechanical drive connections and without externally exposed fluid connections, between such mechanisms and devices.

Abstract: An electrical interlock system for including a power takeoff device operable in a first state to transfer mechanical energy from an associated combustible engine to an associated electric motor and/or generator and operative in a second state to prevent the transfer of mechanical energy from the associated combustible engine to the associated electric motor and/or generator. A relay having a first switch and an energizable portion, is coupled to the power takeoff device, the electric motor and an associated power source, such that when the energizable portion is receiving electrical power from the associated power source, the power takeoff device is in the first state and when the energizable portion is not receiving electrical power from the associated power source, the power takeoff device is in the second state.

Abstract: An electro-hydraulic actuation system (901) includes an unbalanced hydraulic actuator (902) capable of motion in retraction and extension directions during movement of a load (904). A pump (204) provides a flow of fluid to the actuator. A displacement of the pump controls a velocity of the actuator during motion in the retraction and extension directions. An electric motor (202) drives the pump. Speed and direction of the electric motor affects the displacement of the pump. A controller (802) controls the speed and direction of the electric motor. A feedback device (228,248) is operable for sensing a system condition and for providing a feedback signal indicative of the sensed system condition to the controller. The controller is responsive to the feedback signal for determining an occurrence of an over-center load condition and for modifying the speed of the electric motor in response to the occurrence in an attempt to maintain the velocity of the actuator.

Abstract: A method of controlling an electro-hydraulic actuator system having multiple functions includes the steps of: receiving input signals corresponding to a desired operation of the functions of the system; establishing an operating limit for the system; determining an operating characteristic of the system; using the operating limit and the determined operating characteristic to determine a limitation control factor; and influencing the received input signal with the determined limitation control factor for operating the system within the established operating limit.

Abstract: A flow management system capable of providing adjustable hydraulic fluid flow or pressure at a common line to supply bidirectional pumps in electro-hydrostatic actuation systems and conditioning re-circulated hydraulic fluid. The system enables flow sharing between multiple actuation systems and minimization of energy consumption by a power-on-demand approach and/or electrical energy regeneration while eliminating the need for an accumulator. The system has particular application to electro-hydrostatic actuation systems that typically include bi-directional electric motor driven pumps and unbalanced hydraulic actuators connected within closed circuits to provide work output against external loads and reversely recover energy from externally applied loads.

Abstract: An electrical interlock system for including a power takeoff device operable in a first state to transfer mechanical energy from an associated combustible engine to an associated electric motor and/or generator and operative in a second state to prevent the transfer of mechanical energy from the associated combustible engine to the associated electric motor and/or generator. A relay having a first switch and an energizable portion, is coupled to the power takeoff device, the electric motor and an associated power source, such that when the energizable portion is receiving electrical power from the associated power source, the power takeoff device is in the first state and when the energizable portion is not receiving electrical power from the associated power source, the power takeoff device is in the second state.

Abstract: An integrated fluid handling apparatus 10 includes a power take off device 108 having a rotating power take off mechanism 122, a hydraulic pump 104 having a rotating fluid pump mechanism 146, a flow torque tube 106, and an electric motor/generator 102 having a rotating electric power conversion mechanism 173. A rotational power transfer system includes connector devices 128, 138, 166 and 172 that are drivingly connected to and that drivingly connect the mechanisms 122, 146 and 173 in one mode of operation. The electric motor/generator 102 includes heat exchange fluid flow passages that establish a fluid flow path to the inlet of the pump. The mechanisms 122, 146 and 173, and the connector devices 128, 138, 166 and 172 are assembled and used as a whole within a housing, without externally exposed mechanical drive connections and without externally exposed fluid connections, between such mechanisms and devices.